In known machines, e.g., applicants machines for packeting bundles of cigarettes in soft or American and hinged lid type packets respectively capable of a production speed of 400 packets per minute, the bundles of cigarettes are transferred from their bundling zone to packing zone by a compartment conveyor belt with intermittent movement forwards.
During this transfer in the conveyor stationary phase, every compartment is subject, in a set position, to the action of a control device checking the bundle of cigarettes for missing or short or even for faulty cigarettes in the bundle. See for example applicant's U.S. Pat. No. 3,520,394.
In case of finding a faulty bundle, the control device actuate an expulsion device placed further down along the same conveyor in order for the faulty bundle to be taken out.
Further, as known and described in applicant's U.S. application Ser. No. 721,531, now abandoned, in the event of any drawbacks emerging, the control device also sends a stop command to the various wrapping materials feed lines so as to halt the assembly of elements for wrapping the missing or faulty bundle.
In other words the length of foil, the label for the outer wrapper and the State seal intended to cover a bundle of cigarettes missing or expelled because faulty are held with feed lines stationary to await the next fault-free bundle.
This manner of proceeding, without considering the case outside the present context of feed lines for the outer wrappers or labels and State seals, has some negative effects inherent in the structure and behaviour of the foil feed line on the running and output of the packer. The apparatus intended to supply the lengths of foil is in fact particularly complicated, as may be appreciated from the applicant's patent application Ser. No. 721,531, now abandoned, comprising a high number of elements in continuous rotatory movement at the very high speed packer drive.
The high inertia of the masses involved prevents either instant stopping of the apparatus after the missing or faulty bundle has been found or sufficiently fast resumption of work after the pause. As a result when the control devices signal an empty compartment or faulty bundle of cigarettes, the packer is made to run for a suitable time interval at a speed below working level. This has the advantage of helping stop the feed line and thus picking up normal working in stages through an intermediate low speed phase, nonetheless presents the serious drawback of the negative effect on packer output.